Medical practitioners often see patients with ailments caused by soft or hard tissue displacements relative to the surrounding anatomy. Much effort is placed into repositioning the tissue and keeping it in the correct location. A common example is a broken bone, where the doctor repositions the bone and restricts its movement via a cast until the bones are healed.
Shoulder impingement is a clinical syndrome which occurs when the tendons of the rotator cuff muscles become irritated and inflamed as they pass through the passage between the acromion and the humerus, also called the subacromial space. Anything which causes narrowing of this space can result in pain and decreased range of motion.
Impingement can be caused by bony structures such as subacromial spurs (bony projections from the acromion), osteoarthritic spurs on the acromioclavicular joint, variations in the shape of the acromion, thickening or calcification of the coracoacromial ligament or thickening of the subacromial bursa. Likewise, injury or loss of strength of the rotator cuff muscles may cause the humerus to move superiorly, resulting in impingement.
Impingement is usually treated conservatively. Conservative treatment includes rest, cessation of painful activity, and physiotherapy. Physiotherapy treatments would typically focus at maintaining range of movement, improving posture, strength of the muscles of the shoulder and scapula, and reduction of pain. Physiotherapists may employ joint mobilization, interferential therapy, acupuncture, soft tissue therapy, therapeutic taping and scapular and rotator cuff strengthening to improve pain and function. Non-steroidal anti-inflammatory drugs (NSAIDs) and ice packs may also be used for pain relief. Therapeutic injections of corticosteroid and local anesthetic may be used to treat pain from persistent impingement. The total number of injections is generally limited to three due to possible side effects from the corticosteroid. Corticosteroids may cause musculoskeletal disorders. Because of these limitations, conservative treatments have a low success rate.
Surgical interventions may be available to remove the impinging structures, and the subacromial space may be widened by resection of the distal clavicle and excision of osteophytes on the under-surface of the acromioclavicular joint. Also damaged rotator cuff muscles can be surgically repaired. A variety of different devices are used to reposition tissue, such as casts and splints, screws and plates, and spacers such as those used in the spine. These devices may be inadequate for heavily articulatable joints such as the shoulder.
Consequently, it would be advantageous if an apparatus existed that is suitable for maintaining or widening a subacromial space to prevent or treat impingement in heavily articulated joints.